Dynamic quorum for distributed systems

ABSTRACT

Managing a distributed system. Embodiments may allow for a quorum to dynamically change the quorum vote. One example is illustrated in a method. The method includes determining a change to a voter&#39;s level of participation in a cluster. A quorum of voters changes the voter&#39;s voting privileges, based on the change in the voter&#39;s level of participation.

BACKGROUND Background and Relevant Art

Computers and computing systems have affected nearly every aspect ofmodern living. Computers are generally involved in work, recreation,healthcare, transportation, entertainment, household management, etc.

Further, computing system functionality can be enhanced by a computingsystem's ability to be interconnected to other computing systems vianetwork connections. Network connections may include, but are notlimited to, connections via wired or wireless Ethernet, cellularconnections, or even computer to computer connections through serial,parallel, USB, or other connections. The connections allow a computingsystem to access services at other computing systems and to quickly andefficiently receive application data from other computing system.

Interconnected computing systems can often be used as a distributedsystem, where nodes (i.e., individual computing systems) in thedistributed system work together to perform a coordinated computingtask. Some systems allow nodes in a distributed system to vote onwhether or not to perform an action. A quorum is the minimum number ofvotes needed to allow a proposed action to be performed by thedistributed system. A typical quorum is a number of nodes that is amajority of configured nodes for the distributed system. However, if thenumber of active nodes in a distributed computing system falls below thenumber needed for a quorum, the distributed computing system may be madeunable to perform any meaningful functions. While the distributedcomputing system may have sufficient resources to perform functions, theinability to achieve a quorum would render the distributed system unableto come to an agreement as to any functions.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one exemplary technology area where some embodimentsdescribed herein may be practiced.

BRIEF SUMMARY

One embodiment herein is directed to an embodiment practiced in adistributed computing environment. The embodiment includes a method ofmanaging a distributed system. The method includes determining a changeto a voter's level of participation in a cluster. A quorum of voterschanges the voter's voting privileges, based on the change in thevoter's level of participation.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

Additional features and advantages will be set forth in the descriptionwhich follows, and in part will be obvious from the description, or maybe learned by the practice of the teachings herein. Features andadvantages of the invention may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims. Features of the present invention will become more fullyapparent from the following description and appended claims, or may belearned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features can be obtained, a more particular descriptionof the subject matter briefly described above will be rendered byreference to specific embodiments which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments and are not therefore to be considered to be limiting inscope, embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 illustrates an example of a node joining and leaving a cluster;and

FIG. 2 illustrates a method of managing a distributed system.

DETAILED DESCRIPTION

Some embodiments described herein implement a dynamic quorum whichallows for dynamically adjusting a quorum value of the cluster nodes orquorum witnesses based on the state of the cluster node or quorumwitnesses. This can help to ensure cluster survival when the totalnumber of active votes (cluster nodes or cluster quorum witnesses) fallsbelow a pre-specified default or original quorum value. This can help toprevent a cluster from going down if the number of active votes in thecluster falls below a fixed default quorum value.

Embodiments may implement a dynamic quorum which is a feature that helpsadjust the quorum value of a cluster to help achieve higher clusteravailability even when the number of nodes or votes is below a defaultquorum value. Such a cluster could sustain more node crashes and couldcontinue to run a workload for longer duration than in cases withoutdynamic cluster quorum adjustments that would have taken clusters down.In some embodiments, by preventing the cluster from going down,administrators may have an opportunity to connect to the cluster andtake corrective actions when it is determined that nodes in the clusterare going down.

In some embodiments, using a dynamic quorum is an opt-in feature wherecustomers explicitly enable dynamic quorum using a cluster property. Inthe examples illustrated herein, the opt-in feature is enabled by usingthe example cluster property illustrated as ‘EnableDynamicQuorum’.However, other properties or mechanisms could be used. When customersenable the dynamic quorum feature, a cluster service starts todynamically manage votes assigned to individual nodes based on theircurrent state and cluster membership status.

With a dynamic quorum enabled, when a cluster node goes out of clustermembership, the remaining nodes in the cluster membership dynamicallyreduce the out-going node's vote to be 0. This dynamic reduction ofnode's vote allows for adjusting (in this case lowering) the requirednumber of quorum of votes. When the required number of quorum of votesis reduced, the cluster can then sustain even more nodes leaving clustermembership than other systems might allow.

Similarly, when a node joins the cluster membership with dynamic quorumenabled, the nodes in the cluster membership dynamically assign a voteof 1 to the node that joins the cluster. This ensures cluster quorumvalue is calculated correctly when a different node leaves clustermembership.

Referring now to FIG. 1, an example is illustrated. Consider a cluster102 running with 4 nodes 104-1, 104-2, 104-3, and 104-4. Each of thenodes 104-1, 104-2, 104-3, and 104-4 has a vote of 1 as illustrated. Thequorum value for this cluster in this particular example is 3. Threenodes make up a majority of the nodes. One of the nodes 104-4 may crashor otherwise leave the cluster 102. This reduces the number of nodes inactive cluster membership down to 3. Without dynamic quorum, one extranode crash would take down the cluster as there would not be 3 votes fora quorum in the cluster 102. With dynamic quorum, the remaining threenodes in the cluster remove the vote of the out-going node, asillustrated by the phantom representation of the node 104-4 having avote of 0. This brings the quorum value down to 2. Thus, the dynamicallyadjusted cluster 102 can now sustain one extra node crash before takingthe cluster 102 down.

Some embodiments may be implemented such that dynamically adjustedquorum values do not go below a minimum of 2 votes. This may beimportant in some cases with two nodes having a quorum value of 2 inthat no one node can effectively infer that it can continue to run andhost the workload.

In the case of a Node-Disk majority quorum model, with witnesses it maypossible for one node to go down and still maintain the minimum 2 votes.The following illustrates quorum configurations with witnesses. In oneexample, a witness gets a vote, just like a node, and thus there are N+1votes in the system, where N is number of nodes. A quorum is a majorityof configured voters. Dynamic quorum principles apply to thisconfiguration as described previously in that either nodes or witnesscan leave the system. The system could still have sufficient resourcesto perform functions, but previously, the inability to form quorumrenders it useless. However, consider a cluster 102 running with 4 nodes104-1, 104-2, 104-3, 104.4 and configured with a quorum disk witness.The quorum value for this cluster in this particular example is 3. Twoof the nodes 104-3 and 104-4 may crash or otherwise leave the cluster102. With dynamic quorum, the remaining two nodes in the cluster removethe vote of the out-going nodes, as illustrated by the phantomrepresentation of the nodes 104-3 and 104-4 having a vote of 0. Thisbrings the quorum value down to 2. The quorum disk witness itself has avote. Thus, the dynamically adjusted cluster 102 can now sustain oneextra node crash before taking the cluster 102 down.

However, other embodiments may allow the quorum value to go below 2. Inone example, when only two nodes remain, the two remaining nodes willselect one of the nodes to have a vote value of 1 and the other node tohave a vote value of 0. In this case, if the node with the vote value of0 goes down, the cluster can continue to operate with the single nodewith the vote value of 1 performing the cluster functionality. However,if the node with the vote value of 1 goes down, the cluster will beessentially disabled and unable to perform further clusterfunctionality.

Some embodiments may be implemented in the context of a node shutdown.Dynamic vote adjustment can be extended to handle clean node shutdown.For example, and with reference to FIG. 1, in the case of clean nodeshutdown, the node 104-4 that is being shutdown will announce to thenodes 104-1, 104-2, and 104-3 in current cluster membership about itsdeparture and the remaining nodes 104-1, 104-2, and 104-3 would mark theshutting node's vote to 0. This allows, for example, for anadministrator or some automated tool to shutdown nodes still allow forcluster to keep on running below the default quorum of votes. When theadministrator or an automated tool starts the node 104-4, and thestarted node 104-4 joins back in the cluster, the newly joined node'svote is again increased to 1. For example, an administrator or someautomated tool may wish to shutdown nodes during off-peak hours but notcompletely disable the cluster. This would allow this functionality tobe accomplished.

Some embodiments may have functionality for conditions related tocomplete cluster shutdown. When an administrator explicitly chooses toshut the cluster down, some embodiments may identify this situation as aspecial condition. In such embodiments the cluster service will notchange node votes but rather continue to shut down the cluster. Thus,for complete cluster shut-down, the dynamic quorum functionality can beover-ridden.

The following now illustrates a very specific example. It should benoted that other embodiments may use alternative components oralternative functionality. As noted, some embodiments may explicitlyenable dynamic quorum functionality to allow for changing quorum values.Further, some embodiments may include a daemon, illustrated herein as aDynamic Quorum Daemon (DQD) 106. A daemon is a piece of software thatcarries out background tasks. In some embodiment, the DQD could beimplemented as a background application running on each of the nodes104-1, 104-2, 104-3 and 104-4. In the illustrated example, afterenabling dynamic quorum by setting EnableDynamicQuorum cluster propertyto 1, the DQD 106 is activated. In the illustrated example, the DQD 106wakes up every 5 seconds or earlier if an interesting event hasoccurred. Such interesting events may include system failures, requeststo join a cluster, etc. When awake, the DQD 106 checks to see if thereare any adjustment to node votes that are to be made. For example, votescan be removed for nodes that have left or are leaving the cluster 102and/or votes can be given to nodes that have joined or are joining thecluster 102. After performing adjustments to node votes, the DQD 106checks again to determine any interesting events have occurred sincewaking. If none have occurred, the DQD 106 goes back to sleep.

For correctness it is sufficient to either wake up DQD 106 on a timer,or on interesting events. However, it may be useful to use both as dueto oversight or code changes embodiments may miss a particularinteresting event leaving a hole in the algorithm. Using a timer (in thecurrent example, a five second wake timer) guarantees that voteadjustments will be made. Waking on interesting events allows the DQD106 to exhibit faster reaction times.

The DQD 106 can be used to handle unexpected shutdown of nodes or eventhe entire cluster. However in some embodiments, the DQD 106 does notperform any vote adjustment of a node if that node started a gracefulnode shutdown. Similarly, in some embodiments, the DQD 106 does notperform any vote adjustments when a graceful cluster shutdown begins.Rather, prior to graceful node or cluster shutdown, the nodes themselveswill propose that gracefully shutting down nodes, or all nodes in thecluster in the case of a cluster shutdown, have their vote set to 0. Oneexception to this may be when a node is the last quorum vote, in whichcase, the entire cluster may be gracefully shutdown.

The following table lists interesting events, in some embodiments, thatwake up DQD 106 and the DQD's actions for such events. Changes to anode's vote by DQD is done when the rest of the cluster is active.

Event Action Node has finished joining and DQD on the joining node willadjust reported a node-up event its vote from 0 to 1 The set of downednodes has Lowest number node with active changed cluster membership willbring downed nodes vote to zero, one by one An event signals the quorumDQD on every node evaluates if any was reacquired due to a voteadjustments need to be done previously inaccessible witness device nowbeing accessible Node added to the quorum DQD on every node evaluates ifany configuration/node removed vote adjustments need to be done from thequorum configuration/ witness device changed

Various rules may be implemented for determining how vote is adjusted.The following illustrates nine rules used for vote adjustment performedby the DQD 106:

Rule 1: When a cluster 102 is one off quorum, where a cluster isconfigured with a witness/quorum resource and the witness/quorum deviceis temporarily inaccessible and regaining the access to quorum devicewill bring cluster to quorum, no vote adjustments are performed.

Rule 2: When cluster is in a fix quorum mode, when an administrator hasmanually overridden the quorum configuration and forced the system torun despite not achieving a quorum of vote, no downward vote adjustmentsare made. For example, a cluster can have a fixed quorum numberspecified.

Rule 3: DQD 106 does not bring a vote of a node to 1 if a target vote ofthe node is set to 0. In particular, if an administrator indicates thata node should have a vote of 0, the dynamic quorum system will not forcethe vote of the node to 1. An administrator can configure a node to nothave a vote in quorum (irrespective of dynamic quorum), even though itis participating in the system. The vote that the node is configured tohave (either by default or because changed by the administrator) is the“target vote”. The vote that the node currently has, perhaps because itsvote was removed by DQD when it left the system is the “actual nodevote”. The purpose of this rule is to say that, if an administratorconfigures a node to have no vote in the quorum configuration, then theDQD respects the administrator's wishes and does not increase the node'svote. The node's target vote in this case is 0. If an administratorconfigures a node to always have a vote in the quorum configuration,then the DQD respects the administrator's wishes and does not bring thevote of the node down in case the node is no longer part of activecluster/system.

Rule 4: DQD 106 operates on the actual node vote. DQD 106 does notchange the target vote of a node.

Rule 5: A node, when up, will always try to independently bring its ownvote to its target vote. This can be done by the node proposing to thequorum that its vote be adjusted by the quorum to its target vote.

Rule 6: Prior to a graceful shutdown, a node will bring its own vote to0, unless this will result in 0 votes in the cluster, in which case,entire cluster is shutdown.

Rule 7: An active node in a set of active nodes is elected and isresponsible for bringing votes of downed nodes to zero one at a time. Inone embodiment, this may be done using nodes that have unique ids thatcan be numerically compared such that the numerically lowest id node canbe elected. For this rule, there is one node in the set of active nodesdesignated to initiate the adjustment of weights of down nodes. Whichnodes this is can be arbitrary, so long as all active nodes agree onwhich node it is. Choosing the numerically lowest id is a very simpledeterministic way to reach this agreement.

Rule 8: During graceful cluster shutdown, vote node adjustment by thedynamic quorum system should be avoided

Rule 9: If a witness is configured, the DQD 106 does not bring the totalof all node votes in the cluster to below 2.

Embodiments may allow for manual vote adjustment. In particular, manualvote adjustment may be allowed while dynamic quorum is enabled. Forexample, the DQD 106 will honor administrator request to keep a nodevote at zero.

If a target vote is set by an administrator to zero, in some embodimentsDQD 106 will not change node weigh. If target vote is not set or set to1, DQD 106 is free to adjust actual node vote as needed. DQD 106 doesnot change the target vote.

Embodiments may include functionality to fix (or force) quorum mode. Inthese embodiments, when a cluster is started in a fixed quorum, the DQD106 will not adjust missing node votes down to zero. To exit fixedquorum mode, the administrator brings enough nodes up and/or adjusts thetarget votes of other nodes as needed.

Various embodiments may include various features such as thoseillustrated below.

Embodiments may dynamically remove the quorum vote of a cluster node incase of a node crashing, a node shutting down (either gracefully orotherwise) or a provisioned node that is supposed to join a cluster notjoining the cluster during cluster formation.

Embodiments may dynamically remove quorum vote of quorum witness in acase of permanent failure of the quorum witness or if the quorum witnessis persistently offline.

Embodiments may dynamically add quorum vote to a cluster node in thecase of the cluster node successfully joining the cluster.

Embodiments may dynamically add quorum vote to a quorum witness in thecase where the quorum witness successfully joins a quorum afterpermanent failure of the witness or after the witness has beenpersistently offline.

Embodiments may include a property (such as EnableDynamicQuorumillustrated above) to enable/disable dynamic quorum functionality.

Embodiments may include Dynamic Quorum Vote per Cluster Node or QuorumWitness

Embodiments may include interaction with existing quorum policies. Suchpolicies may include Node-Majority with Disk Witness, Node-Majority withFile Share Witness, Simple Node-Majority. Clusters may support varioustypes of quorum witnesses and dynamic quorum functionality can beapplied to any type of quorum witness supported by the cluster. Inparticular, dynamic quorum can be applied to a majority quorumconfiguration with or without a witness. There can be different kinds ofwitnesses, so long as the implementation of the quorum mechanism has theability to associate the witness with a vote. Typically this means thewitness can store data. Further, there can be multiple witnesses

Embodiments may include interaction with manual quorum vote assignments.In particular, embodiments may be designed to allow administrators tomanually set a nodes quorum vote level. In some embodiments, the dynamicquorum functionality will not change this manually assigned level.Similarly, embodiments may include interaction with a fixed quorum modeor a forced quorum mode already supported by the cluster.

Embodiments may include disallowing dynamically removing quorum votes inthe case of entire cluster shutdown.

The following discussion now refers to a number of methods and methodacts that may be performed. Although the method acts may be discussed ina certain order or illustrated in a flow chart as occurring in aparticular order, no particular ordering is required unless specificallystated, or required because an act is dependent on another act beingcompleted prior to the act being performed.

Referring now to FIG. 2, a method 200 is illustrated. The method 200 maybe practiced in a distributed computing environment and includes actsfor managing a distributed system. The method includes determining achange of a voter's level of participation in a distributed system (act202). A voter may be at least one of a node or a witness device. To be awitness device, nodes are able to store data on the device. A witness ismost useful if all nodes can access it (not necessarily simultaneously,but in case one node accessing the device fails, another should be ableto take over). Otherwise, the witness may still be a single point offailure if it is only able to communicate with a single node. A disk isa good witness, especially if it is “physically” shared such that it isaccessible from multiple nodes by some shared storage bus, such as fibrechannel, iSCSI, Serial Attached SCSI, etc. A file share is anotherexample of a device that may be used for a witness. As another example,a web server can be a witness if it can store data on behalf of nodes.For example, the web server may support an HTTP PUT or other commandenabling it to store data on behalf of nodes.

One example of a distributed system includes a cluster system. A voter'smay have its level of participation I the distributed system changed ina number of different ways. For example, the voter may leave thedistributed system. Alternatively, the voter may join the distributedsystem. Alternatively, the voter may become actively leaving thedistributed system. Alternatively, the voter may become actively joiningthe distributed system.

The method 200 further includes a quorum of voters changing the voter'svoting privileges, based on the change in the voter's level ofparticipation (act 204). As will be described further below, voters canhave their voting privileges changed by either being awarded a vote orhaving a vote removed. An example of this is illustrated in FIG. 1 wherenode 104-4 has its votes changed depending on changes to the node'sparticipation level in the cluster 102.

The method 200 may be practiced where determining a change of a voter'slevel of participation in a distributed system includes determining anode is no longer part of the distributed system. In this example,changing the voter's voting privileges includes removing the node'svote.

The method 200 may be practiced where determining a change of a voter'slevel of participation in a distributed system includes determining anode has been added to the distributed system. In this example, changingthe voter's voting privileges includes giving the node a vote.

The method 200 may be practiced where determining a change of a voter'slevel of participation in a distributed system includes determining thatthe node is leaving distributed system. The quorum of voters changingthe voter's voting privileges includes removing the node's vote. Thisincludes the node itself as part of the quorum voting to remove its ownvote to reduce the number of nodes needed for a quorum in thedistributed system. In some embodiments, the node that is leaving in agraceful shutdown scenario may propose to the quorum that its vote beremoved as part of the graceful shutdown.

The method 200 may further include determining that only two nodesremain in the quorum. In some embodiments, the method 200 may, as aresult, deterministically selecting one of the nodes to lose its voteand one of the nodes to retain its vote. As noted, if the node that wasselected to retain its vote were to go down, then the entire distributedsystem would be unable to perform actions that require quorum. However,if the node that was selected to lose its vote were to go down, then thedistributed system could continue to function. This may also apply whendistributed systems have more than two nodes in active membership, butdue to administrator setting explicitly intended/target votes of othernodes to zero, embodiments have only two nodes with votes.

The method 200 may further include receiving user input and as a resultadding or removing votes from one or more nodes. In particular,embodiments may allow for an administrator to manually add or removevotes. Thus, dynamic adjustments may be made to the quorum as well asmanual adjustments.

The method 200 may further include determining that the quorum comprisesthree voters including two nodes and one device. One of the nodes leavesthe distributed system and as a result, the method 200 includesdetermining not to remove the node's vote based on determination thatthe quorum previously comprised three voters including two nodes and onedevice.

Further, the methods may be practiced by a computer system including oneor more processors and computer readable media such as computer memory.In particular, the computer memory may store computer executableinstructions that when executed by one or more processors cause variousfunctions to be performed, such as the acts recited in the embodiments.

Embodiments of the present invention may comprise or utilize a specialpurpose or general-purpose computer including computer hardware, asdiscussed in greater detail below. Embodiments within the scope of thepresent invention also include physical and other computer-readablemedia for carrying or storing computer-executable instructions and/ordata structures. Such computer-readable media can be any available mediathat can be accessed by a general purpose or special purpose computersystem. Computer-readable media that store computer-executableinstructions are physical storage media. Computer-readable media thatcarry computer-executable instructions are transmission media. Thus, byway of example, and not limitation, embodiments of the invention cancomprise at least two distinctly different kinds of computer-readablemedia: physical computer readable storage media and transmissioncomputer readable media.

Physical computer readable storage media includes RAM, ROM, EEPROM,CD-ROM or other optical disk storage (such as CDs, DVDs, etc), magneticdisk storage or other magnetic storage devices, or any other mediumwhich can be used to store desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer.

A “network” is defined as one or more data links that enable thetransport of electronic data between computer systems and/or modulesand/or other electronic devices. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or a combination of hardwired or wireless) to acomputer, the computer properly views the connection as a transmissionmedium. Transmissions media can include a network and/or data linkswhich can be used to carry or desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer. Combinationsof the above are also included within the scope of computer-readablemedia.

Further, upon reaching various computer system components, program codemeans in the form of computer-executable instructions or data structurescan be transferred automatically from transmission computer readablemedia to physical computer readable storage media (or vice versa). Forexample, computer-executable instructions or data structures receivedover a network or data link can be buffered in RAM within a networkinterface module (e.g., a “NIC”), and then eventually transferred tocomputer system RAM and/or to less volatile computer readable physicalstorage media at a computer system. Thus, computer readable physicalstorage media can be included in computer system components that also(or even primarily) utilize transmission media.

Computer-executable instructions comprise, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing device to perform a certain function orgroup of functions. The computer executable instructions may be, forexample, binaries, intermediate format instructions such as assemblylanguage, or even source code. Although the subject matter has beendescribed in language specific to structural features and/ormethodological acts, it is to be understood that the subject matterdefined in the appended claims is not necessarily limited to thedescribed features or acts described above. Rather, the describedfeatures and acts are disclosed as example forms of implementing theclaims.

Those skilled in the art will appreciate that the invention may bepracticed in network computing environments with many types of computersystem configurations, including, personal computers, desktop computers,laptop computers, message processors, hand-held devices, multi-processorsystems, microprocessor-based or programmable consumer electronics,network PCs, minicomputers, mainframe computers, mobile telephones,PDAs, pagers, routers, switches, and the like. The invention may also bepracticed in distributed system environments where local and remotecomputer systems, which are linked (either by hardwired data links,wireless data links, or by a combination of hardwired and wireless datalinks) through a network, both perform tasks. In a distributed systemenvironment, program modules may be located in both local and remotememory storage devices.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or characteristics. The described embodimentsare to be considered in all respects only as illustrative and notrestrictive. The scope of the invention is, therefore, indicated by theappended claims rather than by the foregoing description. All changeswhich come within the meaning and range of equivalency of the claims areto be embraced within their scope.

What is claimed is:
 1. In a distributed computing environment, a methodof managing a distributed system, the method comprising: determining achange of a voter's level of participation in a distributed system,wherein a voter is at least one of a node or a device; and a quorum ofvoters changing the voter's voting privileges, based on the change inthe voter's level of participation.
 2. The method of claim 1, whereindetermining a change of a voter's level of participation in adistributed system comprises determining a node is no longer part of thedistributed system and changing the voter's voting privileges comprisesremoving the node's vote.
 3. The method of claim 1, wherein determininga change of a voter's level of participation in a distributed systemcomprises determining a node has been added to the distributed systemand changing the voter's voting privileges comprises giving the node avote.
 4. The method of claim 1, wherein determining a change of avoter's level of participation in a distributed system comprisesdetermining that the node is leaving distributed system and wherein aquorum of voters changing the voter's voting privileges comprisesremoving the node's vote including the node itself as part of the quorumvoting to remove its own vote to reduce the number of nodes needed for aquorum in the distributed system.
 5. The method of claim 1, furthercomprising determining that only two nodes remain in the quorum and as aresult deterministically selecting one of the nodes to lose its vote andone of the nodes to retain its vote.
 6. The method of claim 1, furthercomprising receiving user input and as a result removing votes from oneor more nodes.
 7. The method of claim 1, further comprising receivinguser input and as a result adding votes to one or more nodes.
 8. Themethod of claim 1, further comprising determining that the quorumcomprises three voters including two nodes and one device, and whereinone of the nodes leaves the distributed system and as a resultdetermining not to remove the node's vote based on determination thatthe quorum previously comprised three voters including two nodes and onedevice.
 9. In a distributed computing environment, one or more computerreadable media comprising computer executable instructions that whenexecuted by one or more processors cause one or more processor toperform the following: determining a change of a voter's level ofparticipation in a distributed system, wherein a voter is at least oneof a node or a device; and changing the voter's voting privileges, basedon the change in the voter's level of participation.
 10. The one or morecomputer readable media of claim 9, wherein determining a change of avoter's level of participation in a distributed system comprisesdetermining a node is no longer part of the distributed system andchanging the voter's voting privileges comprises removing the node'svote.
 11. The one or more computer readable media of claim 9, whereindetermining a change of a voter's level of participation in adistributed system comprises determining a node has been added to thedistributed system and changing the voter's voting privileges comprisesgiving the node a vote.
 12. The one or more computer readable media ofclaim 9, wherein determining a change of a voter's level ofparticipation in a distributed system comprises determining that thenode is leaving distributed system and wherein a quorum of voterschanging the voter's voting privileges comprises removing the node'svote including the node itself as part of the quorum voting to removeits own vote to reduce the number of nodes needed for a quorum in thedistributed system.
 13. The one or more computer readable media of claim9, further comprising determining that only two nodes remain in thequorum and as a result deterministically selecting one of the nodes tolose its vote and one of the nodes to retain its vote.
 14. The one ormore computer readable media of claim 9, further comprising receivinguser input and as a result removing votes from one or more nodes. 15.The one or more computer readable media of claim 9, further comprisingreceiving user input and as a result adding votes to one or more nodes.16. The one or more computer readable media of claim 9, furthercomprising determining that the quorum comprises three voters includingtwo nodes and one device, and wherein one of the nodes leaves thedistributed system and as a result determining not to remove the node'svote based on determination that the quorum previously comprised threevoters including two nodes and one device.
 17. In a distributedcomputing environment, a distributed system configured to dynamicallymanage voters and quorum in the distributed system, the systemcomprising: a plurality of nodes organized as voters in a distributedsystem, wherein the plurality of nodes comprises at least a quorum ofvoters; a voter node in the plurality of nodes, wherein a voter is atleast one of a node or a device and wherein the voter node has its levelof participation in the distributed system changed; a daemon coupled tothe distributed system wherein the daemon is configured to determine thechange of the voter's level of participation in the distributed system;and a quorum of voters changing the voter's voting privileges, based onthe change in the voter's level of participation as determined by thedaemon.
 18. The system of claim 17, wherein determining a change of avoter's level of participation in a distributed system comprisesdetermining a node is no longer part of the distributed system andchanging the voter's voting privileges comprises removing the node'svote.
 19. The system of claim 17, wherein determining a change of avoter's level of participation in a distributed system comprisesdetermining a node has been added to the distributed system and changingthe voter's voting privileges comprises giving the node a vote.
 20. Thesystem of claim 17, wherein determining a change of a voter's level ofparticipation in a distributed system comprises determining that thenode is leaving distributed system and wherein a quorum of voterschanging the voter's voting privileges comprises removing the node'svote including the node itself as part of the quorum voting to removeits own vote to reduce the number of nodes needed for a quorum in thedistributed system.